Epicuro Protective Materials Antimosses' Guard

A friend purchased 3 x 5Litres of Anti-mosses' Guard, one for myself and two for him and his son. We all applied the solutions roughly about the same time, March April (2010). Before the end of 2010 we all noticed that moss & alga was starting to reappear. My friend and I complained directly to epicuro, explaining that the moss & alga was coming back and that their information stated it had residual effects for 2-3 years after applying. We asked if they would forward another batch of Anti-mosses' Guard as this batch seemed to be faulty. They refused to do so and insisted that we had all applied it wrong. We explained that we had all followed their instruction and that it was carried out by 3 different people in 3 different locations, but they still refused to listen and hung the phone up on me. The patio is very slippery & dangers now, strongly suggest not using this product.